Intro(3)

Name

Intro– introduction to functions and libraries

Description

This section describes functions found in various Solaris libraries, other than those functions described in Section 2 of this manual that directly invoke UNIX system primitives. Function declarations can be obtained from the #include files indicated on each page. Pages
are grouped by library and are identified by the library name (or an abbreviation of the library name) after the section number. Collections of related libraries are grouped into volumes as described below. The first volume contains pages describing the contents of each shared library and each
header used by the functions, macros, and external variables described in the remaining volumes.

Library Interfaces and Headers

This volume describes the contents of each shared library and each header used by functions, macros, and external variables described in the remaining volumes.

(3LIB)

The libraries described in this section are implemented as shared objects.

Descriptions of shared objects can include a definition of the global symbols that define the shared objects' public interface, for example SUNW_1.1. Other interfaces can exist within the shared object, for example SUNWprivate.1.1. The public interface
provides a stable, committed set of symbols for application development. The private interfaces are for internal use only, and could change at any time.

(3HEAD)

The headers described in this section are used by functions, macros, and external variables. Headers contain function prototypes, definitions of symbolic constants, common structures, preprocessor macros, and defined types. Each function described in the remaining five volumes
specifies the headers that an application must include in order to use that function. In most cases only one header is required. These headers are present on an application development system; they do have to be present on the target execution system.

Basic Library Functions

The functions described in this volume are the core C library functions that are basic to application development.

(3C)

These functions, together with those of Section 2, constitute the standard C library, libc, which is automatically linked by the C compilation system. The standard C library is implemented as a shared object, libc.so. See libc(3LIB) and the “C Compilation System“ chapter of the ANSI C Programmer's Guide for a discussion. Some functions behave differently
in standard-conforming environments. This behavior is noted on the individual manual pages. See standards(5).

The libpthread and libthread libraries are filter libraries on libc that are used for building multithreaded applications: libpthread implements the POSIX (see standards(5)) threads interface, whereas libthread implements the Solaris threads interface. See MULTITHREADED APPLICATIONS, below.

(3C_DB)

These functions constitute the threads debugging library, libc_db. This library is implemented as a shared object, libc_db.so, but is not automatically linked by the C compilation system. Specify -lc_db on the cc command
line to link with this library. See libc_db(3LIB).

(3MALLOC)

These functions constitute the various memory allocation libraries: libmalloc, libbsdmalloc, libmapmalloc, libmtmalloc, and libumem. Each of these libraries is implemented as a shared
object (libmalloc.so, libbsdmalloc.so, libmapmalloc.so, libmtmalloc.so, and libumem.so). These libraries are not automatically linked by the C compilation system. Specify -lmalloc, -lbsdmalloc, -lmapmalloc, -lmtmalloc, and -lumem to link with, respectively, libmalloc, libbsdmalloc, libmapmalloc, libmtmalloc, and libumem. See libmalloc(3LIB), libbsdmalloc(3LIB), libmapmalloc(3LIB), libmtmalloc(3LIB), and libumem(3LIB).

Networking Library Functions

The functions described in this volume comprise the various networking libraries.

(3COMMPUTIL)

These functions constitute the communication protocol parser utilities library, libcommputil. This library is implemented as a shared object, libcommputil.so, but it is not automatically linked by the C compilation system. Specify -lcommputil on the cc command line to link with this library. See libcommputil(3LIB).

(3DLPI)

These functions constitute the data link provider interface library, libdlpi. This library is implemented as a shared object, libdlpi.so, but it is not automatically linked by the C compilation system. Specify -ldlpi on the cc command line to link with this library. See libdlpi(3LIB).

(3DNS_SD)

These functions constitute the DNS service discovery library, libdns_sd. This library is implemented as a shared object, libdns_sd.so, but it is not automatically linked by the C compilation system. Specify -ldns_sd on the cc command line to link with this library. See libdns_sd(3LIB).

(3GSS)

These functions constitute the generic security services library. This library is implemented as a shared object, libgss.so, but it is not automatically linked by the C compilation system. Specify -lgss on the cc command line
to link with this library. See libgss(3LIB).

(3LDAP)

These functions constitute the lightweight directory access protocol library, libldap. This library is implemented as a shared object, libldap.so, but is not automatically linked by the C compilation system. Specify -lldap on
the cc command line to link with this library. See ldap(3LDAP).

(3NSL)

These functions constitute the network service library, libnsl. This library is implemented as a shared object, libnsl.so, but is not automatically linked by the C compilation system. Specify -lnsl on the cc command
line to link with this library. See libnsl(3LIB).

Many base networking functions are also available in the X/Open networking interfaces library, libxnet. See section (3XNET) below for more information on the libxnet interfaces.

(3RESOLV)

These functions constitute the resolver library, libresolv. This library is implemented as a shared object, libresolv.so, but is not automatically linked by the C compilation system. Specify -lresolv on the cc command
line to link with this library. See libresolv(3LIB).

(3RPC)

These functions constitute the remote procedure call libraries, librpcsvc and librpcsoc. The latter is provided for compatibility only; new applications should not link to it. Both libraries are implemented as shared objects, librpcsvc.so and librpcsoc.so, respectively. Neither library is automatically linked by the C compilation system. Specify -lrpcsvc or -lrpcsoc on the cc command line to link with these libraries. See librpcsvc(3LIB).

(3SASL)

These functions constitute the simple authentication and security layer library, libsasl. This library is implemented as a shared object, libsasl.so, but it is not automatically linked by the C compilation system. Specify -lsasl on
the cc command line to link with this library. See libsasl(3LIB).

(3SIP)

These functions constitute the session initiation protocol library, libsip. This library is implemented as a shared object, libsip.so, but it is not automatically linked by the C compilation system. Specify -lsip on the cc command line to link with this library. See libsip(3LIB).

(3SLP)

These functions constitute the service location protocol library, libslp. This library is implemented as a shared object, libslp.so, but it is not automatically linked by the C compilation system. Specify -lslp on the cc command line to link with this library. See libslp(3LIB).

(3SOCKET)

These functions constitute the sockets library, libsocket. This library is implemented as a shared object, libsocket.so, but is not automatically linked by the C compilation system. Specify -lsocket on the cc command
line to link with this library. See libsocket(3LIB).

(3XNET)

These functions constitute X/Open networking interfaces which comply with the X/Open CAE Specification, Networking Services, Issue 4 (September, 1994). This library is implemented as a shared object, libxnet.so, but is not automatically linked by the C compilation
system. Specify -lxnet on the cc command line to link with this library. See libxnet(3LIB) and standards(5) for compilation information.

Under all circumstances, the use of the Sockets API is recommended over the XTI and TLI APIs. If portability to other XPGV4v2 (see standards(5)) systems
is a requirement, the application must use the libxnet interfaces. If portability is not required, the sockets interfaces in libsocket and libnsl are recommended over those in libxnet. Between the XTI and TLI APIs, the XTI interfaces (available with libxnet) are recommended over the TLI interfaces (available with libnsl).

Curses Library Functions

The functions described in this volume comprise the libraries that provide graphics and character screen updating capabilities.

(3CURSES)

The functions constitute the following libraries:

libcurses

These functions constitute the curses library, libcurses. This library is implemented as a shared object, libcurses.so, but is not automatically linked by the C compilation system. Specify -lcurses on the cc command
line to link with this library. See libcurses(3LIB).

libform

These functions constitute the forms library, libform. This library is implemented as a shared object, libform.so, but is not automatically linked by the C compilation system. Specify -lform on the cc command
line to link with this library. See libform(3LIB).

libmenu

These functions constitute the menus library, libmenu. This library is implemented as a shared object, libmenu.so, but is not automatically linked by the C compilation system. Specify -lmenu on the cc command
line to link with this library. See libmenu(3LIB).

libpanel

These functions constitute the panels library, libpanel. This library is implemented as a shared object, libpanel.so, but is not automatically linked by the C compilation system. Specify -lpanel on the cc command
line to link with this library. See libpanel(3LIB).

(3PLOT)

These functions constitute the grapnics library, libplot. This library is implemented as a shared object, libplot.so, but is not automatically linked by the C compilation system. Specify -lplot on the cc command
line to link with this library. See libplot(3LIB).

(3XCURSES)

These functions constitute the X/Open curses library, located in /usr/xpg4/lib/libcurses.so. This library provides a set of internationalized functions and macros for creating and modifying input and output to a terminal screen. Included in this library are
functions for creating windows, highlighting text, writing to the screen, reading from user input, and moving the cursor. X/Open Curses is designed to optimize screen update activities. The X/Open Curses library conforms fully with Issue 4 of the X/Open Extended Curses specification. See libcurses(3XCURSES).

Extended Library Functions, Vol. 1

The functions described in this volume comprise the following specialized libraries:

(3BSM)

These functions constitute the Solaris auditing library, libbsm. This library is implemented as a shared object, libbsm.so, but is not automatically linked by the C compilation system. Specify -lbsm on the cc command
line to link with this library. See libbsm(3LIB).

(3CFGADM)

These functions constitute the configuration administration library, libcfgadm. This library is implemented as a shared object, libcfgadm.so, but is not automatically linked by the C compilation system. Specify -lcfgadm on
the cc command line to link with this library. See libcfgadm(3LIB).

(3CONTRACT)

These functions constitute the contract management library, libcontract. This library is implemented as a shared object, libcontract.so, but is not automatically linked by the C compilation system. Specify -lcontract on the cc command line to link with this library. See libcontract(3LIB).

(3CPC)

These functions constitute the CPU performance counter library, libcpc, and the process context library, libpctx. These libraries are implemented as shared objects, libcpc.so and libpctx.so, respectively,
but are not automatically linked by the C compilation system. Specify -lcpc or -lpctx on the cc command line to link with these libraries. See libcpc(3LIB) and libpctx(3LIB).

(3DAT)

These functions constitute the direct access transport library, libdat. This library is implemented as a shared object, libdat.so, but is not automatically linked by the C compilation system. Specify -ldat on the cc command
line to link with this library. See libdat(3LIB).

(3DEVID)

These functions constitute the device ID library, libdevid. This library is implemented as a shared object, libdevid.so, but is not automatically linked by the C compilation system. Specify -ldevid on the cc command line to link with this library. See libdevid(3LIB).

(3DEVINFO)

These functions constitute the device information library, libdevinfo. This library is implemented as a shared object, libdevinfo.so, but is not automatically linked by the C compilation system. Specify -ldevinfo on the cc command line to link with this library. See libdevinfo(3LIB).

(3ELF)

These functions constitute the ELF access library, libelf, (Extensible Linking Format). This library provides the interface for the creation and analyses of “elf” files; executables, objects, and shared objects. libelf is implemented
as a shared object, libelf.so, but is not automatically linked by the C compilation system. Specify -lelf on the cc command line to link with this library. See libelf(3LIB).

(3EXACCT)

These functions constitute the extended accounting access library, libexacct, and the project database access library, libproject. These libraries are implemented as shared objects, libexacct.so and libproject.so,
respectively, but are not automatically linked by the C compilation system. Specify -lexacct or -lproject on the cc command line to link with these libraries. See libexacct(3LIB) and libproject(3LIB).

(3FCOE)

These functions constitute the Fibre Channel over Ethernet port management library. This library is implemented as a shared object, libfcoe.so, but is not automatically linked by the C compilation system. Specify -lfcoe on the cc command
line to link with this library. See libfcoe(3LIB).

(3FM)

These functions constitute the fault management events library. This library is implemented as a shared object, libfmevent.so, but is not automatically linked by the C compilation system. Specify -lfmevent on the cc command
line to link with this library. See libfmevent(3LIB).

(3FSTYP)

These functions constitute the file system type identification library. This library is implemented as a shared object, libfstyp.so, but is not automatically linked by the C compilation system. Specify -lfstyp on the cc command
line to link with this library. See libfstyp(3LIB).

Extended Library Functions, Vol. 2

The functions described in this volume comprise the following specialized libraries:

(3GEN)

These functions constitute the string pattern-matching and pathname manipulation library, libgen. This library is implemented as a shared object, libgen.so, but is not automatically linked by the C compilation system. Specify -lgen on
the cc command line to link with this library. See libgen(3LIB).

(3HBAAPI)

These functions constitute the common fibre channel HBA information library, libhbaapi. This library is implemented as a shared object, libhbaapi.so, but is not automatically linked by the C compilation system. Specify -lhbaapi on
the cc command line to link with this library. See libhbaapi(3LIB).

(3ISCSIT)

These functions constitute the iSCSI Management library, libiscsit. This library is implemented as a shared object, libiscsit.so, but is not automatically linked by the C compilation system. Specify -liscsit on the cc command
line to link with this library. See libiscsit(3LIB).

(3KSTAT)

These functions constitute the kernel statistics library, which is implemented as a shared object, libkstat.so, but is not automatically linked by the C compilation system. Specify -lkstat on the cc command line to link with
this library. See libkstat(3LIB).

(3KVM)

These functions allow access to the kernel's virtual memory library, which is implemented as a shared object, libkvm.so, but is not automatically linked by the C compilation system. Specify -lkvm on the cc command line to
link with this library. See libkvm(3LIB).

(3LAYOUT)

These functions constitute the layout service library, which is implemented as a shared object, liblayout.so, but is not automatically linked by the C compilation system. Specify -llayout on the cc command line to link with
this library. See liblayout(3LIB).

(3LGRP)

These functions constitute the locality group library, which is implemented as a shared object, liblgrp.so, but is not automatically linked by the C compilation system. Specify -llgrp on the cc command line to link with this
library. See liblgrp(3LIB).

(3M)

These functions constitute the mathematical library, libm. This library is implemented as a shared object, libm.so, but is not automatically linked by the C compilation system. Specify -lm on the cc command
line to link with this library. See libm(3LIB).

(3MAIL)

These functions constitute the user mailbox management library, libmail. This library is implemented as a shared object, libmail.so, but is not automatically linked by the C compilation system. Specify -lmail on the cc command
line to link with this library. See libmail(3LIB).

(3MP)

These functions constitute the integer mathematical library, libmp. This library is implemented as a shared object, libmp.so, but is not automatically linked by the C compilation system. Specify -lmp on the cc command
line to link with this library. See libmp(3LIB).

(3MPAPI)

These functions constitute the Common Mulitipath Management library, libMPAPI. This library is implemented as a shared object, libMPAPI.so, but is not automatically linked by the C compilation system. Specify -lMPAPI on the cc command line to link with this library. See libMPAPI(3LIB).

(3MVEC)

These functions constitute the vector mathematical library, libmvec. This library is implemented as a shared object, libmvec.so, but is not automatically linked by the C compilation system. Specify -lmvec on the cc command
line to link with this library. See libmvec(3LIB).

Extended Library Functions, Vol. 3

The functions described in this volume comprise the following specialized libraries:

(3NVPAIR)

These functions constitute the name–value pair library, libnvpair. This library is implemented as a shared object, libnvpair.so, but is not automatically linked by the C compilation system. Specify -lnvpair on the cc command line to link with this library. See libnvpair(3LIB).

(3PAM)

These functions constitute the pluggable uuthentication module library, libpam. This library is implemented as a shared object, libpam.so, but is not automatically linked by the C compilation system. Specify -lpam on the cc command line to link with this library. See libpam(3LIB).

(3PAPI)

These functions constitute the Free Standards Group Open Printing API (PAPI) library, libpapi. This library is implemented as a shared object, libpapi.so, but is not automatically linked by the C compilation system. Specify -lpapi on
the cc command line to link with this library. See libpapi(3LIB).

(3PICL)

These functions constitute the PICL library, libpicl. This library is implemented as a shared object, libpicl.so, but is not automatically linked by the C compilation system. Specify -lpicl on the cc command
line to link with this library. See libpicl(3LIB) and libpicl(3PICL).

(3PICLTREE)

These functions constitute the PICL plug-in library, libpicltree. This library is implemented as a shared object, libpicltree.so, but is not automatically linked by the C compilation system. Specify -lpicltree on the cc command
line to link with this library. See libpicltree(3LIB) and libpicltree(3PICLTREE).

(3POOL)

These functions constitute the pool configuration manipulation library, libpool. This library is implemented as a shared object, libpool.so, but is not automatically linked by the C compilation system. Specify -lpool on the cc command line to link with this library. See libpool(3LIB).

(3PROJECT)

These functions constitute the project database access library, libproject. This library is implemented as a shared object, libproject.so, but is not automatically linked by the C compilation system. Specify -lproject on the cc command line to link with this library. See libproject(3LIB).

(3REPARSE)

These functions constitute the reparse point library, libreparse. This library is implemented as a shared object, libreparse.so, but is not automatically linked by the C compilation system. Specify -lreparse on the cc command
line to link with this library. See libreparse(3LIB).

(3RSM)

These functions constitute the remote shared memory library, librsm. This library is implemented as a shared object, librsm.so, but is not automatically linked by the C compilation system. Specify -lrsm on the cc command
line to link with this library. See librsm(3LIB).

Extended Library Functions, Vol. 4

The functions described in this volume comprise the following specialized libraries:

(3SCF)

These functions constitute the object-caching memory allocation library, libscf. This library is implemented as a shared object, libscf.so, but is not automatically linked by the C compilation system. Specify -lscf on the cc command line to link with this library. See libscf(3LIB).

(3SEC)

These functions constitute the file access control library, libsec. This library is implemented as a shared object, libsec.so, but is not automatically linked by the C compilation system. Specify -lsec on the cc command
line to link with this library. See libsec(3LIB).

(3SECDB)

These functions constitute the security attributes database library, libsecdb. This library is implemented as a shared object, libsecdb.so, but is not automatically linked by the C compilation system. Specify -lsecdb on the cc command line to link with this library. See libsecdb(3LIB).

(3SNMP)

These functions constitute the SNMP libraries, libssagent and libssasnmp. These libraries are implemented as shared objects, libssagent.so and libssasnmp.so, respectively, but are not automatically
linked by the C compilation system. Specify -lssagent or -lssasnmp on the cc command line to link with these libraries. See libssagent(3LIB) and libssasnmp(3LIB).

(3STMF)

These functions constitute the SCSI Target Mode Framework library, libstmf. This library is implemented as a shared object, libstmf.so, but is not automatically linked by the C compilation system. Specify -lstmf on the cc command line to link with this library. See libstmf(3LIB).

(3SYSEVENT)

These functions constitute the system event library, libsysevent. This library is implemented as a shared object, libsysevent.so, but is not automatically linked by the C compilation system. Specify -lsysevent on the cc command
line to link with this library. See libsysevent(3LIB).

(3TECLA)

These functions constitute the interactive command-line input library, libtecla. This library is implemented as a shared object, libtecla.so, but is not automatically linked by the C compilation system. Specify -ltecla on
the cc command line to link with this library. See libtecla(3LIB).

(3TNF)

These functions constitute the TNF libraries, libtnf, libtnfctl, and libtnfprobe. These libraries are implemented as shared objects, libtnf.so, libtnfctl.so, and libtnfprobe.so, respectively, but are not automatically linked by the C compilation system. Specify -ltnf, -ltnfctl, or -ltnfprobe on the cc command line to link with these libraries. See libtnfctl(3TNF) and libtnfctl(3LIB).

(3TSOL)

These functions constitute the Trusted Extensions library, libtsol, and the Trusted Extensions network library, libtsnet. These libraries are implemented as shared objects, libtsol.so and libtsnet.so, but are not
automatically linked by the C compilation system. Specify -ltsol or -ltsnet on the cc command line to link with these libraries. See libtsol(3LIB) and libtsnet(3LIB).

(3UUID)

These functions constitute the universally unique identifier library, libuuid. This library is implemented as a shared object, libuuid.so, but is not automatically linked by the C compilation system. Specify -luuid on the cc command line to link with this library. See libuuid(3LIB).

(3VOLMGT)

These functions constitute the volume management library, libvolmgt. This library is implemented as a shared object, libvolmgt.so, but is not automatically linked by the C compilation system. Specify -lvolmgt on the cc command
line to link with this library. See libvolmgt(3LIB).

(3WSREG)

These functions constitute the product install registry library, libwsreg. This library is implemented as a shared object, libwsreg.so, but is not automatically linked by the C compilation system. Specify -lwsreg on the cc command line to link with this library. See libwsreg(3LIB).

(3XTSOL)

These functions constitute the Trusted Extensions to the X windows library, libXtsol. This library is implemented as a shared object, libXtsol.so, but is not automatically linked by the C compilation system. Specify -lX11 and then -lXtsol on the cc command line to link with this library. See libXtsol(3LIB).

Multimedia Library Functions

(3MLIB)

These functions constitute the mediaLib library, libmlib. This library is implemented as a shared object, libmlib.so, but is not automatically linked by the C compilation system. Specify -lmlib on the cc command
line to link with this library. See libmlib(3LIB).

(3MMS)

These functions constitute the Media Management System library, libmms. This library is implemented as a shared object, libmms.so, but is not automatically linked by the C compilation system. Specify -lmms on the cc command
line to link with this library. See libmms(3LIB).

Definitions

A character is any bit pattern able to fit into a byte on the machine. In some international languages, however, a “character” might require more than one byte, and is represented in multi-bytes.

The null character is a character with value 0, conventionally represented in the C language as \ 0. A character array is a sequence of characters. A null-terminated character array (a string) is a sequence of characters, the last
of which is the null character. The null string is a character array containing only the terminating null character. A null pointer is the value that is obtained by casting 0 into a pointer. C guarantees that this value will not match that of any legitimate pointer, so many
functions that return pointers return NULL to indicate an error. The macro NULL is defined in <stdio.h>. Types of the form size_t are defined in the appropriate headers.

Multithreaded Applications

Both POSIX threads and Solaris threads can be used within the same application. Their implementations are completely compatible with each other; however, only POSIX threads guarantee portability to other POSIX-conforming environments.

When compiling a multithreaded application, the -mt option must be specified on the command line.

There is no need for a multithreaded application to link with -lthread. An application must link with -lpthread only when POSIX semantics for fork(2) are desired. When an application is linked with -lpthread, a call to fork() assumes the behavior fork1(2) rather
than the default behavior that forks all threads.

When compiling a POSIX-conforming application, either the _POSIX_C_SOURCE or _POSIX_PTHREAD_SEMANTICS option must be specified on the command line. For POSIX.1c-conforming applications, define the _POSIX_C_SOURCE flag to be >= 199506L:

cc-mt [ flag... ] file... -D_POSIX_C_SOURCE=199506L-lpthread

For POSIX behavior with the Solaris fork() and fork1() distinction, compile as follows:

cc-mt [ flag... ] file... -D_POSIX_PTHREAD_SEMANTICS

For Solaris threads behavior, compile as follows:

cc-mt [ flag... ] file...

Unsafe interfaces should be called only from the main thread to ensure the application's safety.

MT-Safe interfaces are denoted in the ATTRIBUTES section of the functions and libraries manual pages (see attributes(5)). If a manual
page does not state explicitly that an interface is MT-Safe, the user should assume that the interface is unsafe.

Realtime Applications

The environment variable LD_BIND_NOW must be set to a non-null value to enable early binding. Refer to the “When Relocations are Processed” chapter in Linker and Libraries Guide for additional
information.

Files

INCDIR

usually /usr/include

LIBDIR

usually either /lib or /usr/lib (32–bit) or either /lib/64 or /usr/lib/64 (64–bit)

LIBDIR/*.so

shared libraries

Acknowledgments

Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at http://www.opengroup.org/bookstore/.

The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation.

In the following statement, the phrase ``this text'' refers to portions of the system documentation.

Portions of this text are reprinted and reproduced in electronic form in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004
by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
online at http://www.opengroup.org/unix/online.html.

This notice shall appear on any product containing this material.

See Also

Diagnostics

For functions that return floating-point values, error handling varies according to compilation mode. Under the -Xt (default) option to cc, these functions return the conventional values 0, ±HUGE, or NaN when
the function is undefined for the given arguments or when the value is not representable. In the -Xa and -Xc compilation modes, ±HUGE_VAL is returned instead of ±HUGE. (HUGE_VAL and HUGE are
defined in math.h to be infinity and the largest-magnitude single-precision number, respectively.)

Notes

None of the functions, external variables, or macros should be redefined in the user's programs. Any other name can be redefined without affecting the behavior of other library functions, but such redefinition might conflict with a declaration in an included header.

The headers in INCDIR provide function prototypes (function declarations including the types of arguments) for most of the functions listed in this manual. Function prototypes allow the compiler to check for correct usage of these functions in the user's program.
The lint program checker can also be used and will report discrepancies even if the headers are not included with #include statements. Definitions for Sections 2 and 3C are checked automatically. Other definitions can be included by using the -l option
to lint. (For example, -lm includes definitions for libm.) Use of lint is highly recommended. See the lint chapter in Performance Profiling Tools

Users should carefully note the difference between STREAMS and stream. STREAMS is a set of kernel mechanisms that support the development of network services and data communication drivers. It is composed of utility routines, kernel facilities, and a set of data
structures. A stream is a file with its associated buffering. It is declared to be a pointer to a type FILE defined in <stdio.h>.

In detailed definitions of components, it is sometimes necessary to refer to symbolic names that are implementation-specific, but which are not necessarily expected to be accessible to an application program. Many of these symbolic names describe boundary conditions and system limits.

In this section, for readability, these implementation-specific values are given symbolic names. These names always appear enclosed in curly brackets to distinguish them from symbolic names of other implementation-specific constants that are accessible to application programs by headers.
These names are not necessarily accessible to an application program through a header, although they can be defined in the documentation for a particular system.

In general, a portable application program should not refer to these symbolic names in its code. For example, an application program would not be expected to test the length of an argument list given to a routine to determine if it was greater than {ARG_MAX}.